title: Do long-term changes in relative maxillary arch width affect buccal-corridor ratios in extraction and nonextraction treatment?
abstract: BACKGROUND
  Our aims were to evaluate long-term maxillary arch width changes in orthodontic patients treated with and without premolar extractions and to provide a potential link to the buccal-corridor ratios.
  
  
  METHODS
  Dental casts of 34 extraction and 32 nonextraction orthodontic patients with Class I malocclusions were digitized and evaluated before treatment (T1), at posttreatment (T2), and at postretention (T3). The mean postretention times for the extraction and the nonextraction groups were 5 years 2 months and 4 years 10 months, respectively. Specific arch width measurements were made on the anatomic y-axis of the casts between the most labial aspects of the anatomic dental arch immediately distal to the incisive papilla, the farthest point posteriorly of the conjunction of the third lateral and medial rugae on the midpalatal raphe and at an individually constant distance from the incisive papilla. Arch width changes were calculated and compared statistically to determine whether the dental arches were narrower after extraction treatment and at postretention.
  
  
  RESULTS
  All maxillary arch width measurements remained virtually stable after extraction therapy and at the postretention follow-up. Significant increases were recorded for all maxillary arch width measurements in the nonextraction group after treatment (mean changes, 1.37-2.05 mm). Posterior arch width measurements decreased significantly between T2 and T3 (mean change, 0.5 mm). Mean changes between T1 and T2 were significant between the 2 groups for all measurements (P <0.05). Only the mean change in posterior arch width was significant between the 2 groups in the postretention period (P <0.05).
  
  
  CONCLUSIONS
  Extraction treatment did not result in narrower maxillary dental arches, whereas nonextraction treatment slightly expanded the dental arch.
authors.affiliation: Department of Orthodontics, The University of Texas/Houston Dental Branch, Houston, TX, USA. sercan.akyalcin@uth.tmc.edu
authors.forename: Sercan
authors.initials: S
authors.lastname: Akyalcin
authors.forename: Aslihan Ertan
authors.initials: AE
authors.lastname: Erdinc
authors.forename: Banu
authors.initials: B
authors.lastname: Dincer
authors.forename: Ram S
authors.initials: RS
authors.lastname: Nanda
mesh_terms: D000293:Adolescent; D001641:Bicuspid / Q000601:surgery*; D002508:Cephalometry; D002610:Cheek / Q000473:pathology*; D003481:Cuspid / Q000473:pathology; D003724:Dental Arch / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007180:Incisor / Q000473:pathology; D008137:Longitudinal Studies; D008297:Male; D008311:Malocclusion, Angle Class I / Q000628:therapy*; D008437:Maxilla / Q000473:pathology*; D008963:Molar / Q000473:pathology; D009811:Odontometry; D018704:Orthodontic Retainers; D010159:Palate / Q000473:pathology; D012690:Serial Extraction